Adjustable venturi gas scrubber

ABSTRACT

An annular venturi gas scrubber in which the throat is adjusted to compensate for changes in gas flow rate by suspending the central conical baffle from a central vertical rod which extends upwards from the apex of the conical baffle and which is vertically movable. Two venturi gas scrubbers are also provided in series within a container and in vertical alignment, with the upper first scrubber having an adjustable throat. The first scrubber removes entrained solid particles from the gas stream and the second scrubber removes gaseous contaminants such as sulfur dioxide.

14 1 Sept. 12, 1972 t n e t S e t a 64 S 486 in n 4444 99 5555100.. I 66 .HH/ mmmm mmmmz 1111.. 6666 mm .2 t u" mi ou N wman mhnmfll .1 hl l maoa h EHMLCwv 556780 6666677 9999999 1111111 58 5626 I 1 7757760 76399004924 804 k .w m l\ N d r 3 m b Q r 8 mL x] E W m mm rt PA 9 7 0 2 6 N w pA m [57] ABSTRACT An annular venturi gas scrubber in which the throat isadjusted to compensate for changes in gas flow rate by suspending thecentral conical baffle from a central vertical rod which extends upwardsfrom the apex of the conical baffle and which is vertically movable.

5 5., 00 3004 S HZS H 2 722 $64 9 3 I 492 5Dd95 ,/1 21 1103, 5 B911 22 u41 l 9 510N021 5 9 x a ,1" 500 3/ 4 2 "002.1 26 n 5., 2 50000 5 1 820 22 "1 9 ml M569 "U H WH 6 m m m m 9 Thu "5 2 "5 D 5 L 1 C 0 6 d 2 5 mm UIF Two venturi gas scmbbers are also provided in series within acontainer and in vertical alignment, with the per first scrubber havingan adjustable throat. The

[56] References Cited UNITED STATES PATENTS P first scrubber removesentraine the d solid particles from as stream and the second scrubberremoves gasedioxide.

3,597,901 8/1971 Heeney........................55/457 g 3,601,374 8/1971Wheeler......................35/241 ouscomaminamssuch assulfur 2,964,30412/1960 Rice....................26l/DIG. 54

3,085,793 4/1963 Pike etal............26l/DIG 54 14 Claims, 3 DrawingFigures PATENTEDSEHZ 1m 3.690.044

sum 1 or 3 Y I/f Ill 1/ JOHN G. BORSTA INVENTOR.

PAIENTEnm 12 m2 3.690.044 SHEET 2 BF 3 JOHN PATENIEU SE? 1 2 I972 SHEET3 OF a o co 0300 0 JOHN G. B ORESTA INVENTOR.

BY Q

/ AGENT ADJUSTABLE VENTURI GAS SCRUBBER BACKGROUND OF THE INVENTION 1.Field of the Invention The invention relates to an improved apparatusfor the scrubbing of a gas stream to remove entrained solid particlesand other contaminants such as mist, vapors, or noxious gaseouscomponents such as sulfur dioxide. Numerous industrial or commercialfacilities generate hot waste gas streams which are discharged to theatmosphere. These streams may be laden with entrained solids, mists,vapors or gaseous contaminants such as sulfur dioxide, which must beremoved prior to atmospheric discharge in order to prevent air pollutionor to recover valuable components. Among such facilities may bementioned furnaces or boilers in which a carbonaceous or hydrocarbonfuel which may contain sulfur is burned, incinerators, iron cupolafurnaces, steamelectric power plants, oxygen steel converters, sulfideore toasters, and black liquor furnaces in wood pulp processingfacilities. The entrained solids in the hot discharge gas stream mayconsist of soot, fly ash, iron oxide particles or various types of dust.In many instances, especially in older existing facilities, the gasstream is directly discharged to the atmosphere through a stack, whichserves to disperse the entrained solids, sulfur dioxide, sparks or mistand vapors into the upper atmosphere and thus prevents localized falloutof these contaminants in the surrounding area. In recent years, however,more stringent air pollution regulations have been enacted in manycommunities, which have necessitated the provision of adequatefacilities or apparatus for treating the stack or waste gases so as toremove entrained or contained contaminants and prevent air pollution. Inmany instances, the installation of conventional devices such as bagfilters is not warranted due to the cost of such facilities, and theprior art devices generally fail to compensatefor variations in gas flowrate, such as is encountered in periodic cyclic or batch-type processeswhich generate or discharge gas streams at varying or intermittent flowrates.

2. Description of the Prior Art Numerous devices have been provided inthe prior art for the wet scrubbingof gas streams to remove entrainedsolid particles. Among the devices which provide a venturi passage orventuri-like scrubbing effect may be mentioned those of U.S. Pat. Nos.3,317,197; 3,262,685; 3,085,793 and 3,116,348; and U.S. patentapplications Nos. 753,583 filed Aug. 19, 1968 now U.S. Pat. No.3,544,086 and 808,517 filed Mar. 19, 1969 now U.S. Pat. No. 3,584,440.The provision of two venturi gas scrubbers in series, with direct flowof gas and all scrubbing liquid through both venturis, is shown inCanadian Patent No. 788,802; British Patent No. 1,007,452; and ChemicalEngineering, issue of Nov. 6, 1967, page 20. Other devices and apparatusassemblages are disclosed in U.S. Pat. No. 3,077,714 and CanadianPatents Nos. 684,884 and 670,150. Other art relative to gas washing ordispersion of a liquid into a gas includes U.S. Pat. Nos. 2,033,404;2,575,359; 2,086,671; 3,323,290; 2,661,195; 2,354,678; 2,409,088;3,045,990 and 2,414,718.

In the present invention, an adjustable annular venturi scrubber isprovided in which the central conical baffle is suspended from avertical rod which extends upwards from an attachment at the apex of theconical baffle, to upper means for vertical displacement or adjustmentof the rod and conical baffle, which adjustment thereby modifies thedimension of the annular venturi throat to compensate for changes in gasflow rate, pressure or composition. The rod extends upwards through avertically oriented coaxial and generally cylindrical and concentricouter conduit, which extends downwards and terminates at a restrictedopening adjacent to the apex of the conical baffle. Scrubbing liquid ispassed into the conduit at a controlled rate, so .as to maintain aliquid body in the conduit which acts as a liquid seal against upwardsgas flow between the rod and conduit. In one embodiment of theinvention, especially applicable to the scrubbing of flue or stack gasescontaining fly ashand sulfur dioxide, two vertically oriented venturiscrubbers are provided in series within a container, with the firstupper venturi scrubber being adjustable and serving to remove solidsparticles from a feed gas stream initially containing entrained solidsand a gaseous or vaporous contaminant. The scrubbing liquid containingsolids particles is separated from the resulting gas stream containinggaseous contaminant, which is passed within the container to the lowerventuri for scrubbing with a liquid solution which is a specificabsorbent for the gaseous contaminant.

The principal advantage of the adjustable annular venturi of the presentinvention is that the apparatus may be modified to accommodate forvarying gas flow rates or compositions by adjustment or verticaldisplacement of the central conical baffle, by means of structure-whichis nonclogging and free of liquid seals which can become inoperative orleaky due to entrance of grit or other solids particles derived from thegas stream. Another advantage is that the adjustable venturi apparatusis simple and readily fabricated. An advantage of the dual or twoventuris in series embodiment of the invention is that a compactcoacting arrangement is provided and that a slurry of scrubbing liquidcontaining separated solid particles is removed independently of thesecond scrubber for removal of gaseous contaminant, which permitseconomies in the usage of scrubbing liquid and facilitates regenerationor other processing of the second absorbent or scrubbing liquid solutioncontaining the gaseous contaminant separately removed from the gasstream and dissolved in the second solution, which is produced free ofthe solids originally present in the gas stream. This advantage isespecially important when a slurry is used as the second scrubbingsolution for removal of gaseous contaminant, since prior removal ofsolids from the gas stream in the first venturi prevents the buildup ofinert solids in the circulating slurry.

It is an object of the present invention to provide an improvedapparatus for scrubbing a gas stream with a liquid scrubbing medium, inorder to remove contaminants from the gas stream.

Another object is to provide an improved venturi scrubber for scrubbinggas streams.

A further object is to provide an improved annular venturi scrubber withan adjustable throat, for scrubbing gas streams.

An additional object is to provide an adjustable annular venturiscrubber, which may be adjusted or modified to compensate for variationsin gas flow rate or to produce a desired degree of gas scrubbingeffectiveness.

Still another object is to provide an improved apparatus for scrubbing agas stream containing solid particles and gaseous contaminant, withseparate removal of solids and gaseous contaminant.

Still a further object is to provide an improved twostage venturiscrubber.

These and other objects and advantages of the present invention willbecome evident from the description which follows.

DESCRIPTION OF THE DRAWINGS AND PREFERRED EMBODIMENTS Referring now tothe drawings,

FIG. 1 is a sectional elevation view of the adjustable annular venturiof the present invention,

FIG. 2 is a sectional plan view of a portion of FIG. 1, taken on section22, and

FIG. 3 is a sectional elevation view of one embodiment of the two stageventuri scrubber of the invention.

Referring now to FIG. 1, the contaminant-laden gas stream 1 is derivedfrom a source such as those mentioned supra, or other sources such as achemical or metallurgical process facility, or the like. The contaminantin gas stream 1 may consist of entrained discrete solid particles suchas fly ash, a mist or fog, or vaporous or gaseous constituents such assulfur dioxide. Stream 1 is typically a flue gas containing fly ash andsulfur dioxide and derived from the combustion of a carbonaceous solidfuel such as coal or a liquid hydrocarbon fuel such as crude oil or fueloil or Bunker C residual oil derived from petroleum refining.

The pressure of stream 1 is preferably measured typically by theprovision of pressure sensing device 2 which may contain a flexiblediaphragm or bulb or other sensing means, and a pneumatic or electricsignal corresponding to inlet pressure is transmitted from device 2 vialine 3. The gas stream passes from device 2 via stream 4 to thehorizontal cylindrical inlet conduit 5, which passes the gas stream intothe device of the invention for scrubbing with a liquid scrubbingsolution or slurry. Conduit 5 extends to the vertically orientedcylindrical container section 6, which is the upper section of the gasscrubbing container. A cover plate 7 is provided at the top of section6, and a vertically oriented generally cylindrical conduit 8 extendsdownwards into the container from plate 7. Conduit 8 is coaxial withcontainer 6, and conduit 8 is preferably tapered to a decreasingdiameter in a downwards direction, and in some cases conduit 8 may be inthe form of an inverted frusto-conical baffle. A horizontal splash plate9 is provided at the top of conduit 8 to prevent splashing or spillingof the scrubbing liquid solution or slurry stream 10, which passes vianozzle 11 into conduit 8 at a controlled rate, so that a pool or body ofscrubbing liquid is maintained in conduit 8. The liquid retained inconduit 8 acts as a liquid seal against upwards flow of gas from thecontainer section A vertical cylindrical sleeve 12 extends coaxiallywithin the lower portion and through the lower end of conduit 8. Aplurality of spaced apart spacers 13 are disposed within sleeve 12 andextend between sleeve 12 and the vertical rod or shaft 14, which isvertically movable or adjustable as will appear infra. The spacers 13are preferably round or spherical shapes, however elements 13 may alsobe oval or elliptical in shape or of other suitable form in suitableinstances. A frusto-conical flare skirt 86 depends from sleeve 12 inmost instances, in order to insure uniform distribution of the liquidflowing downwards in the annular passage between sleeve 12 and rod 14.The vertical rod 14 is preferably cylindrical and extends downwardsthrough conduit 8 and sleeve 12. A conical baffle 15 is attached to thelower end of rod 14, with the upper apex of baffle 15 being welded orotherwise attached to the end of rod 14. An inverted frusto-conicalbaffle 16 is provided in most cases, with baffle 16 depending downwardsfrom the bottom of conical baffle 15, so that baffles 15 and 16 aresuspended from rod 14 and move vertically together with rod 14. Thedownflowing liquid solution or slurry flowing down from between sleeve12 and rod 14 flows downwards on the outer surface of baffle 15 and isentrained into the high velocity gas stream adjacent to the lower end ofbaffle 15.

Returning to the upper container section 6, a frustoconical baffle 17depends from the lower portion of section 6, and a lower verticalcylindrical container section 18 depends coaxially downwards from baffle17. A shelf 19 in the form of a flat horizontal annular ring-shapedbaffle extends inwards from the upper end or portion of containersection 18, and scrubbing liquid or slurry stream 20 is passed vianozzles 21 into container 18 onto shelf 19. The nozzles 21 arepreferably horizontal and tangential to container 18, with the nozzles21 discharging portions of stream 20 in tandem onto shelf 19 so thatstream 20 flows on shelf 19 in a substantially circular flow pattern.The scrubbing liquid or slurry stream 20 flows from shelf 19 onto theupper surface of the inverted frusto-conical baffle 22, which dependsdownwards from the inner circular edge of shelf 19 and is coaxially andconcentrically disposed about and spaced from the central conical baffle15. The baffle 22 coacts with baffle 15 to form the converging sectionof an annular venturi gas scrubbing passage. The scrubbing liquid orslurry stream 20 flows downwards on the upper surface of baffle 22 andis entrained inwards into the highly accelerated high velocity gasstream adjacent to the lower terminus of baffle 22. As mentioned supra,the scrubbing liquid or slurry stream flowing downwards on the outersurface of conical baffle 15 is entrained outwards into the highlyaccelerated high velocity gas stream adjacent to the lower terminus ofbaffle 15, with the gas stream being accelerated to high velocity byflowing downwards through the annular converging venturi section definedbetween baffles 15 and 22. The baffle 15 diverts the gas stream againstthe baffle 22 for impact and removal of entrained solids. The liquidsolution or slurry portions, which are entrained into the high velocitygas stream, are dispersed into small droplets which effectively scrubthe gas stream and remove contaminants, by virtue of a shearing actionof the high velocity gas against the liquid.

A vertical cylindrical baffle 23 depends coaxially downwards from baffle22, and baffle 23 serves to partially define the throat section of theventuri passage and to conduct the mixture of scrubbed gas and liquid orslurry droplets into the lower portion of container 18, in which theliquid or slurry phase containing contaminant removed from the gasstream is separated from the scrubbed gas phase. The scrubbed gas streamreverses direction in the lower part of container 18, and flows upwardsthrough the annular passage between baffle 23 and container 18. Asuitable annular entrainment separator 24 extends between baffle 23 andcontainer section 18, to remove entrained liquid droplets or mist fromthe rising scrubbed gas stream. Unit 24 will preferably consist of ahorizontally oriented annular mesh filter pad as shown, or a packed bed,a plurality of trays or impingement baffles, or the like. Collectedliquid flows or drips downwards from unit 24 to the lower part ofcontainer section 18. The scrubbed gas stream flows out of containersection 18 via conduit 25 as stream 26. Conduit 25 extends fromcontainer section 18 below shelf 19 or below the upper end of baffle 22,and in this embodiment of the invention, conduit 25 extends fromcontainer 18 above entrainment separator 24 and below shelf 19. Thescrubbed gas stream 26 flows through pressure sensing device 27, whichis generally similar in configuration and function to unit 2 describedsupra, and the scrubbed gas stream next passes from unit 27 via stream28 to suitable disposal or further processing. In instances when the gasstream being scrubbed is a waste gas such asflue gas, stream 28 willgenerally pass to a stack or the like for dispersion to the atmosphere.

Returning to unit 27, the measurement of gas pressure is converted to anelectrical or pneumatic signal which passes via line 29 to controller30, which also receives the signal conveyed byline 3 and compares thetwo pressure signals to derive a measurement of gas pressure dropthrough the scrubbing device. The gas pressure drop is controlled byunit 30, generally to provide constant pressure drop regardless offluctuations or changes in gas flow rate, by regulating the flow ofinstrument air stream 31, which passes through unit 30 at a controlledrate or pressure as stream 32, which passes via pipe 33 to air cylinder34. The upper end of rod 14 extends upwards into cylinder 34 andterminates at piston 35, so that changes in the pressure of instrumentair stream 32 pneumatically activates the piston 35 within cylinder 34to regulate the vertical displacement of rod 14 and attached bafiles and16 and thereby modify the throat opening in the annular venturi scrubberin accordance with changes in gas flow rate or pressure.

Returning to container section 18, the scrubbing liquid or slurry ladenwith entrained or dissolved contaminant is collected in the lowercollection section 36 which is typically in the form of an invertedconical baffle. Scrubbing liquid solution or slurry is removed from thebottom of section 36 via duct 37 as stream 38, which is passed tosuitable disposal or treatment. Stream 38 may be physically orchemically processed for regeneration, prior to recycle via streams 10and 20.

Referring now to FIG. 2, a sectional plan view of a portion of FIG. 1 isshown, to illustrate the coaxial or concentric arrangement of elements14, 12, 8, 86 and 15, as well as the upper set of spaced apart spacers13 extending between the central rod 14 and sleeve 12.

Referring now to FIG. 3, a sectional elevation view of a preferredembodiment of the invention is shown, in which two venturi scrubbers areprovided for series scrubbing of the gas stream in a single container,in which the upper venturi scrubber is adjustable and removes entrainedsolid particulate contaminant from the gas stream while the lowerventuri has a fixed throat and removes gaseous contaminant from the gasstream, using a selective liquid absorbent which dissolves the gaseouscontaminant. The apparatus of FIG. 3 will be described relative to thescrubbing of flue or stack gas derived from the combustion of asulfur-containing fuel such as coal, fuel oil, crude oil, Bunker Cresidual oil derived from petroleum refining etc. The flue gas stream inthis case will contain entrained solid particles of fly ash as well asgaseous sulfur dioxide contaminant.

The upper adjustable annular venturi scrubber of FIG. 3 is preferablysimilar in configuration and function to the scrubber of FIG. 1described supra, and this section of FIG. 3 device will therefore beonly briefly described. Scrubbing liquid stream 39, which preferablyconsists of water, passes into the vertically oriented cylindrical orinverted frusto-conical conduit 40, which is provided with upper splashplate 41. A waste flue gas is passed into upper vertical cylindricalcontainer section 42 below upper horizontal cover plate 43 via therectangular inlet 44, and flows downwards external to conduit 40. Acoaxial central cylindrical rod 45 is vertically disposed within conduit40, and extends downwards from an upper means for vertical rodadjustment or displacement, not shown, and terminates below the lowerend of conduit 40. A vertical cylindrical sleeve 46 is spaced betweenrod 45 and the lower end of conduit 40 by the plurality of spaced apartcircular spacers 47 which extend between rod 45 and sleeve 46. A lowerfrusto-conical flare skirt 48 depends from sleeve 46.

The scrubbing liquid stream 39 is passed into conduit 40 at a controlledrate, so that a body of liquid, which acts as a liquid seal against gasflow, is maintained in conduit 40, and liquid flows downwards betweensleeve 46 and rod 45 at a restricted rate. The downflowing liquid flowsonto the outer surface of conical baffle 49 which depends from rod 45,with the apex of baffle 49 being attached to the lower end of rod 45.The liquid film or layer flowing downwards on baffle 49 is entrainedinto the high velocity gas stream adjacent to the base of the conicalbaffle 49, and an inverted frustoconical baffle 50 depending from baflle49 is preferably provided to diminish gas turbulence.

Returning to container inlet section 42, a vertical frusto-conicalbaffle section 51 extends downwards and outwards from section 42 to avertical cylindrical container section 52, which depends downwards frombaffle 51 and is provided with nozzle means or the like, not shown, forentry of scrubbing liquid streams 53 into the container. Streams 53preferably consist of water or other scrubbing liquid similar to streams39. Streams 53 are passed onto the circular horizontal annular shelf 54,and the main vertically oriented cylindrical container section 55depends downwards from shelf 54. Container section 55 may depend fromthe outer edge of shelf 54, or directly below section 52, or any similarconfiguration may be adopted in practice. An inverted frusto-conicalbaffle 56 depends from the inner edge of shelf 54, and streams 53 flowfrom shelf 54 onto baffle 56 and downwards as a film or layer on theupper surface of baffle 56.

The waste gas stream is accelerated to high velocity while flowingdownwards through the annular converging venturi passage defined betweenbaffles 49 and 56, and the scrubbing liquid entrained from the lowerends of baffles 49 and 56 into the high velocity gas stream is dispersedinto a large number of small droplets which effectively scrub the gasstream and remove solid fly ash particles. The resulting mixture ofliquid droplets containing fly ash particles, and gas phasesubstantially free of fly ash, passes downwards from the convergingventuri passage into the coaxial cylindrical baffle 57, which dependsfrom baffle 56. The gas phase reverses direction below the lower end ofbaffle 57, and flows upwards through the annular packed bed 58 disposedbetween baffle 57 and the concentric outer vertical cylindrical baffle59. The liquid phase collects in the retention baffle 60, which isgenerally in the form of an inverted conical or funnel-shaped baffledepending from baffle 59. The liquid phase in receptacle 60 willgenerally be in the form of a slurry due to contained solid particles offly ash.

The gas phase passes upwards through packed bed 58, which acts as anentrainment separator to remove residual liquid droplets which collectin receptacle 60. The gas phase discharged upwards above bed 58 reversesdirection above the upper end of baffle 59, and flows downwards throughthe outer annular passage between baffle 59 and container 55. Theresulting downflowing annular gas stream is diverted inwards and into asecond and lower annular venturi scrubbing passage of fixed throatdimension by the inverted frusto-conical baffle 61, which extendsdownwards and inwards from the wall of container 55 below the lower endof bafi'le 59.

A liquid solution or slurry stream 62 is passed via inclined pipe 63into manifold 64. Stream 62 is selective absorbent for the gaseouscontaminant in the gas stream, which in the present instance of flue gasscrubbing consists of sulfur dioxide. Stream 62 in this case usuallyconsists of an aqueous solution or slurry containing a dissolvedalkaline component such as the hydroxide or carbonate of sodium,potassium, calcium or magnesium or the like. The aqueous alkalinesolution or slurry passes from manifold 64 into the plurality of spacedapart dependent spray nozzles 65, which extend downwards from manifold64 and spray the alkaline solution or slurry downwards into the lowerannular venturi passage.

Further aqueous alkaline scrubbing solution or slurry is passed viastream 66 into inclined pipe 67, which conducts the absorbent solutioninto the device for gaseous contaminant removal, with stream 66generally being similar in composition and function to stream 62. Stream66 is passed via pipe 67 into the vertical cylindrical distributionbaffle 68, which preferably depends coaxially from unit 60 and ispreferably provided with a dependent lower frusto-conical flare skirt69, which is disposed about the upper end of central conical baffle 70.The coaxial central baffle 70 is fixed in place, de-

pendent from unit 60, and provides for an annular venturi throat sectionof fixed dimension. An inverted frusto-conical baffle 71 preferablydepends from bafile to prevent gas turbulence in the device, and liquidsolution or slurry stream 66 flows downwards from within member 68 ontothe surface of baffle 70, and is entrained from the lower end of baffle70 into the highly accelerated and high velocity gas stream.

A central slurry removal pipe 72 extends vertically downwards from unit60 through the apex and central axis of baffle 70, to an inclined pipe73 which conducts the slurry stream 74 collected upon unit 60 tosuitable disposal, which may include settling or filtration and suitablewaste disposal as by fly ash dumping or the like.

The central conical baffle 70 coacts with concentric outer invertedfrusto-conical baffle 75 to provide a vertical converging section of thesecond annular venturi passage, in which the gas stream is divertedagainst baffle 75. Baffle 75 is attached to the wall of container 55 bythe substantially horizontal annular circular shelf 76, and scrubbingliquid solution or slurry streams 77, which are generally similar incomposition and function to streams 62 and 66, are passed onto shelf 76by nozzle means or the like, not shown, with the absorbent solution orslurry then flowing downwards on baffle 75 for entrainment into the gasstream from the lower end of baffle 75 The several liquid streams 62, 66and 77 are entrained or sprayed into the gas stream in the secondannular venturi passage, which is of fixed throat dimension, and gaseouscontaminant such as sulfur dioxide is absorbed into the liquid phase andmay react with the alkaline medium to form sulfites, bisulfites or thelike.

A frusto-conical baffle 78 depends downwards from the lower end ofbaffle 75 for pressure regain, and a vertical cylindrical baffle 79depends downwards from the lower end of bafile 78 and serves to conductthe mixture of liquid droplets and scrubbed gas phase downwards into alower gas-liquid separating section. The gas phase discharged frombaffle or conduit 79 reverses direction below the lower end of section79, and flows outwards and upwards through packed bed 80, which servesto removeentrained liquid droplets from the gas phase. The fullyscrubbed gas phase, now

substantially free of entrained fly ash or other solid par ticles, dueto scrubbing in the upper adjustable annular venturi scrubber, andsubstantially free of gaseous contaminants such as sulfur dioxide due toscrubbing in the lower fixed throat annular venturi scrubber, is removedfrom container 55 between shelf 76 and bed 80 via conduit 81 as stream82.

Scrubbing liquid solution or slurry laden with absorbed gaseouscontaminant is collected in the lower inverted conical or funnel-shapedsection 83 which depends from container 55, and is removed via outletpipe 84 as stream 85, which is passed to suitable disposal orregeneration.

As is evident from the description supra, numerous alternatives withinthe scope of the present invention will occur to those skilled in theart. The various liquid distribution shelves 19, 54 or 76 may be omittedin some instances, or horizontal weirs which may be serrated or notchedmay be provided in some cases. Other suitable means for distribution ofliquid onto the surface of the central conical baffie 15, 49 or 70 maybe provided in practice. Stream 74 may in some cases contain avery'minor proportion of dissolved contaminant derived from the gasstream scrubbing in the upper venturi. Various means for verticaladjustment or movement of rods 14 or 45 may be adopted in practice, suchas various types of gearing or handwheels which may be manuallyadjustable. Reference to a scrubbing liquid will be understood toencompass a scrubbing slurry, with the scrubbing slurry containing solidparticles as well as a liquid phase.

In some instances, stream may contain a small proportion of entrainedsolid particles, especially when stream 38 is processed for partialsolids removal and recycled. In this case, nozzle 11 will be tangentialto conduit 8 so as to provide for tangential entry of stream 10 intoconduit 8 and cyclonic or circular flow of liquid downwards withinconduit 8, so as to cause deposition of solids against the inner wall ofconduit 8 and the formation of a central region of clean liquid whichflows downwards adjacent to rod 14 and through sleeve 12. Periodic oreventual removal of solids from the lower annular space between sleeve12 and conduit 8 will then be required. In this case, an annular removalring may be mounted at the lower end of conduit 8, with the ringextending between conduit 8 and sleeve 12 and being periodically removedduring shutdown periods to permit removal of accumulated solids fromconduit 8.

I claim:

1. An apparatus for scrubbing a contaminant from a gas stream withscrubbing liquid which comprises a vertically oriented cylindricalcontainer, a vertical rod, said rod extending coaxially downwards intosaid container, a conical baffle, said conical baffle dependingdownwards from said rod with the apex of said conical baffle beingattached to the lower end of said rod, whereby said conical baffle iscoaxially mounted within said container, means to vertically displacesaid rod, whereby the elevation of said conical baffle within saidcontainer is adjusted, a vertically oriented inverted frusto-conicalconduit, said conduit being coaxially mounted about said rod at theupper end of said container, a vertical cylindrical sleeve, said sleevebeing coaxially mounted between said rod andthe lower end of saidconduit by a plurality of fixed spacers which are spaced apart andextend between said rod and said sleeve, means to pass a first stream ofscrubbing liquid into said conduit at a controlled rate, whereby saidconduit is maintained at least partially filled with scrubbing liquid bythe restricted opening between said rod and said sleeve and therebymaintains a liquid seal against upwards gas flow through said conduit,and whereby said first stream of scrubbing liquid flows downwards in theannular passage between said rod and said sleeve, onto the apex of saidconical baffle, and downwards on the outer surface of said conicalbaffle, an inverted frusto-conical baffle, said inverted frusto-conicalbaffle depending coaxially downwards within said container from an uppercontiguous connection with the inner wall of said container, saidinverted frusto-conical baffie being spaced from and concentricallyabout said conical baffle, whereby a downwardly converging annular gasflow passage is defined between said conical bafile and said invertedfrusto-conical baffle, means to pass a second stream of scrubbing liquiddownwards on the inner surface of said inverted frusto-conical baffle,means to pass a contaminant-laden gas stream into said container abovesaid baffles, whereby said gas stream is accelerated to high velocity byflowing downwards through said converging annular gas flow passage andsaid first and second streams of scrubbing liquid are entrained into thehigh velocity gas stream from the lower ends of said bafiles, saidcontaminant being thereby entrained in the resulting liquid droplets,means to remove the resulting scrubbing liquid containing entrainedcontaminant from the lower portion of said container, and meansextending from said container below the upper end of said invertedfrusto-conical baffie to remove the resulting scrubbed gas stream fromsaid container.

2. The apparatus of claim 1, in which said means to vertically displacesaid vertical rod are adjusted in proportion to change in the pressuredifferential between the pressure of said contaminant-laden gas streamand the pressure of said scrubbed gas stream.

3. The apparatus of claim 1, in which said means to vertically displacesaid rod is a compressed air cylinder mounted about the upper end ofsaid rod, with the upper end of said rod forming the piston of said aircylinder, together with means to adjust the pressure of the air passedto said air cylinder.

4. The apparatus of claim 1, in which a frusto-conical skirt bafiledepends downwards from the lower end of said sleeve and concentricallyadjacent to the apex of said conical baffle.

5. The apparatus of claim 1, in which a vertical cylindrical baffledepends coaxially downwards from said inverted frusto-conical bafflewithin said container.

6. The apparatus of claim 5, in which annular substantially horizontalmeans for separation of entrained liquid droplets extends between saidvertical cylindrical baffle and said vertically oriented container, andsaid means extending from said container to remove the resultingscrubbed gas stream from said container is disposed between said meansfor separation of entrained liquid droplets and the upper end of saidinverted frusto-conical baffle.

7. An apparatus for scrubbing solid and gaseous contaminants from a gasstream which comprises a vertically oriented cylindrical container, afirst vertically oriented venturi scrubber within said container, saidfirst venturi scrubber being defined by an upper inverted frusto-conicalbaffie which provides a converging section, and a throat section belowsaid inverted frusto-conical baffle, said first venturi scrubber beingcoaxially disposed in the upper section of said container and providedwith means to adjust the venturi throat section to compensate forvariation in gas flow, means to pass a gas stream containing solid andgaseous contaminants into said container above said first venturiscrubber, whereby said gas stream flows downwards through said firstventuri scrubber and is accelerated to high velocity, means to pass afirst scrubbing liquid stream into said first venturi scrubber, wherebysaid first scrubbing liquid stream scrubs said gas stream in said firstventuri scrubber and removes solid contaminants, means below said firstventuri scrubber to separate first scrubbing liquid containing entrainedsolids from the resulting gas stream, means to remove the separatedfirst scrubbing liquid containing entrained solids from said container,said resulting gas stream containing gaseous contaminant and beingsubstantially free of solid contaminant, a second vertically orientedventuri scrubber within said container, said second venturi scrubberbeing defined by an upper inverted frusto-conical baffle which providesa converging section, and a throat section below said invertedfrusto-conical baffle, said second venturi scrubber being coaxiallydisposed in the lower section of said container and provided with afixed throat section of constant dimensions, means within said containerto pass said resulting gas stream containing gaseous contaminant fromthe upper section of said container downwards through said secondventuri scrubber, whereby said gas stream is accelerated to highvelocity, means to pass a second scrubbing liquid stream into saidsecond venturi'scrubber, said second scrubbing liquid stream being aselective absorbent for said gaseous contaminant present in saidresulting gas stream, whereby said second scrubbing liquid stream scrubssaid gas stream in said second venturi scrubber and dissolves gaseouscontaminant, means below said second venturi scrubber to separate secondscrubbing liquid containing dissolved contaminant from the residual gasstream, means extending from said container to remove the separatedsecond scrubbing liquid containing dissolved contaminant from saidcontainer, and means extending from said container to remove saidresidual gas stream of diminished contaminants content from saidcontainer said first and second venturi scrubbers being annular venturiscrubbers, each venturi scrubber being provided witha central-conicalbaffle which is coaxial with said container, together with means to passscrubbing liquid downwards on the surface of said central conicalbaffle, said central conical baffle being coaxial with and spacedcentrally within said inverted frusto-conical baffle whereby saidcentral conical baffle and said inverted frusto-conical baffle define anannular converging gas flow passage, and means to pass scrubbing liquiddownwards on the upper surface of said inverted frusto-conical baffle,the central conical baffle of said first venturi scrubber beingvertically moveable whereby the throat section of said first venturiscrubber is adjustable in dimension.

8. The apparatus of claim 7, in which said first venturi scrubberincludes a first coaxial cylindrical baffle which depends downwards fromsaid upper inverted frusto-conical baffle, a central means below saidcoaxial cylindrical baffle for removal of separated first scrubbingliquid containing entrained solids from said container, a second coaxialcylindrical baffle within said container for gas diversion, saiddiversion baffle being spaced from the wall of said container andextending upwards from said central removal means and concentricallyexternal to said first cylindrical baffle and terminating below saidupper inverted frusto-conical baffle, and annular substantiallyhorizontal means for separation of entrained liquid droplets from saidresulting gas stream, said annular separation means extending betweensaid first cylindrical baffle and said second cylindrical bafile,whereby said resulting gas stream flows downwards through said firstcylindrical baffle, upwards through the annular passage between saidfirst cylindrical bafile and said second cylindrical baffle, anddownwards to said second venturi scrubber through the annular passagebetween said second cylindrical bafile and said container.

9. The apparatus of claim 7, in which said gaseous contaminant is sulfurdioxide, and said second scrubbing liquid stream comprises an aqueoussolution containing a dissolved alkaline component selected from thegroup consisting of the hydroxides and carbonates of sodium, potassium,calcium and magnesium.

10. The apparatus of claim 7, in which a horizontal circular liquiddistribution manifold is disposed above the throat section of the secondannular venturi scrubber, a plurality of spray nozzles depend downwardsfrom said manifold, and means are provided to pass second scrubbingliquid to said manifold, whereby second scrubbing liquid is sprayeddownwards into the throat section of said second annular venturiscrubber.

11. The apparatus of claim 7, in which a vertical rod extends coaxiallydownwards into said container, the conical baffle of said firstvertically oriented annular venturi scrubber depending downwards fromsaid rod with the apex of said conical baffle being attached to thelower end of said rod, whereby said conical baffle is coaxiallysuspended within said container, together with means to verticallydisplace said rod, whereby the elevation of said conical baffle withinsaid container is adjusted and said first vertically oriented annularventuri scrubber is thereby provided with an adjustable throat section.

12. The apparatus of claim 11, in which said means to pass firstscrubbing liquid downwards on the surface of the central conical baffleof said first annular venturi scrubber is means for discharge of firstscrubbing liquid at the apex of said conical baffle comprising avertically oriented inverted frusto-conical conduit, said conduit beingcoaxially mounted about said rod at the upper end of said container, thelower end of said conduit having at least one restricted opening fordownwards liquid flow adjacent to the apex of said conical baffle,together with means to pass first scrubbing liquid into said conduit ata controlled rate, whereby said conduit is maintained at least partiallyfilled with scrubbing liquid by said restricted opening and therebymaintains a liquid seal against upwards flow of said contaminantladengas stream through said conduit.

13. The apparatus of claim 12, in which a vertical cylindrical sleeve iscoaxially mounted between said rod and the lower end of said conduit bya plurality of fixed spacers which are spaced apart and extend betweensaid rod and said sleeve, whereby said first scrubbing liquid flowsdownwards in the annular passage between said rod and said sleeve.

14. An apparatus for scrubbing solid and gaseous contaminants from a gasstream which comprises a vertically oriented cylindrical container, avertical rod, said rod extending coaxially downwards into saidcontainer, a first vertically oriented venturi scrubber within saidcontainer and below said rod, said first venturi scrubber being definedby a first central conical baffle and a first inverted frusto-conicalbaffle coaxially disposed in the upper portion of said container, saidfirst conical baffle depending downwards from said rod with the apex ofsaid conical baffle being attached to the lower end of said rod, wherebysaid conical baffle is coaxially mounted within said container, means tovertically displace said rod, whereby the elevation of said conicalbaffle within said container is adjusted to compensate for variation ingas flow, a vertically oriented inverted frusto-conical conduit, saidconduit being coaxially mounted about said rod at the upper end of saidcontainer, a vertical cylindrical sleeve, said sleeve being coaxiallymounted between said rod and the lower end of said conduit by aplurality of fixed spacers which are spaced apart and extend betweensaid rod and said sleeve, means to pass a first stream of scrubbingliquid into said conduit at a controlled rate, whereby said conduit ismaintained at least partially filled with scrubbing liquid by therestricted opening between said rod and said sleeve and therebymaintains a liquid seal against upwards gas flow through said conduit,and whereby said first stream of scrubbing liquid flows downwards in theannular passage between said rod and said sleeve, onto the apex of saidfirst conical baffle, and downwards on the outer surface of said firstconical baffle, said first inverted frusto-conical baffle dependingcoaxially downwards within said container from an upper contiguousconnection with the inner wall of said container, said first invertedfrusto-conical baffle being spaced from and concentrically about saidfirst conical baffle, whereby a downwardly converging annular gas flowpassage is defined between said first conical baffle and said firstinverted frusto-conical baffle, means to pass a second stream ofscrubbing liquid downwards on the inner surface of said first invertedfrusto-conical baffle, means to pass a gas stream containing solid andgaseous contaminants into said container above said first venturiscrubber, whereby said gas stream flows downwards through the convergingpassage between said first conical bafi'le and said first invertedfrusto-conical baffie and is accelerated to high velocity, and wherebysaid first and second streams of contaminant,

scrubbing liquid are entrained into the high velocity gas stream fromthe lower ends of said first baffles, solid contaminant being therebyentrained in the resulting liquid droplets, means below said firstventuri scrubber to separate scrubbing liquid containing entrainedsolids from the resulting gas stream, means to remove the separatedscrubbing liquid containing entrained solids from said container, saidresulting gas stream containing gaseous contaminant and beingsubstantially free of solid contaminant, a second vertically orientedventuri scrubber within said container, said second venturi scrubberbeing defined by a second central conical baffle and a second invertedfrusto-conical baffle which provide a converging section, and a throatsection below said second baffles, said second venturi scrubber beingcoaxially disposed in the lower section of said container and providedwith a fixed throat section of constant dimensions, means within saidcontainer to pass said resulting gas stream containing gaseouscontaminant from the upper section of said container downwards throughsaid second venturi scrubber, whereby said gas stream is accelerated tohigh velocity, means to pass a stream of liquid absorbent for saidgaseous contaminant into said second venturi scrubber, whereby saidliquid absorbent scrubs said gas stream in said second venturi scrubberand dissolves gaseous means below said second venturi scrubber toseparate liquid absorbent containing dissolved contaminant from theresidual gas stream, means extending from said container to remove theseparated liquid absorbent containing dissolved contaminant from saidcontainer, and means extending from said container to remove saidresidual gas stream of diminished contaminants content from saidcontainer.

1. An apparatus for scrubbing a contaminant from a gas stream withscrubbing liquid which comprises a vertically oriented cylindricalcontainer, a vertical rod, said rod extending coaxially downwards intosaid container, a conical baffle, said conical baffle dependingdownwards from said rod with the apex of said conical baffle beingattached to the lower end of said rod, whereby said conical baffle iscoaxially mounted within said container, means to vertically displacesaid rod, whereby the elevation of said conical baffle within saidcontainer is adjusted, a vertically oriented inverted frusto-conicalconduit, said conduit being coaxially mounted about said rod at theupper end of said container, a vertical cylindrical sleeve, said sleevebeing coaxially mounted between said rod and the lower end of saidconduit by a plurality of fixed spacers which are spaced apart andextend between said rod and said sleeve, means to pass a first stream ofscrubbing liquid into said conduit at a controlled rate, whereby saidconduit is maintained at least partially filled with scrubbing liquid bythe restricted opening between said rod and said sleeve and therebymaintains a liquid seal against upwards gas flow through said conduit,and whereby said first stream of scrubbing liquid flows downwards in theannular passage between said rod and said sleeve, onto the apex of saidconical baffle, and downwards on the outer surface of said conicalbaffle, an inverted frusto-conical baffle, said inverted frusto-conicalbaffle depending coaxially downwards within said container from an uppercontiguous connection with the inner wall of said container, saidinverted frusto-conical baffle being spaced from and concentricallyabout said conical baffle, whereby a downwardly converging annular gasflow passage is defined between said conical baffle and said invertedfrustoconical baffle, means to pass a second stream of scrubbing liquiddownwards on the inner surface of said inverted frusto-conical baffle,means to pass a contaminant-laden gas stream into said container abovesaid baffles, whereby said gas stream is accelerated to high velocity byflowing downwards through said converging annular gas flow passage andsaid First and second streams of scrubbing liquid are entrained into thehigh velocity gas stream from the lower ends of said baffles, saidcontaminant being thereby entrained in the resulting liquid droplets,means to remove the resulting scrubbing liquid containing entrainedcontaminant from the lower portion of said container, and meansextending from said container below the upper end of said invertedfrusto-conical baffle to remove the resulting scrubbed gas stream fromsaid container.
 2. The apparatus of claim 1, in which said means tovertically displace said vertical rod are adjusted in proportion tochange in the pressure differential between the pressure of saidcontaminant-laden gas stream and the pressure of said scrubbed gasstream.
 3. The apparatus of claim 1, in which said means to verticallydisplace said rod is a compressed air cylinder mounted about the upperend of said rod, with the upper end of said rod forming the piston ofsaid air cylinder, together with means to adjust the pressure of the airpassed to said air cylinder.
 4. The apparatus of claim 1, in which afrusto-conical skirt baffle depends downwards from the lower end of saidsleeve and concentrically adjacent to the apex of said conical baffle.5. The apparatus of claim 1, in which a vertical cylindrical baffledepends coaxially downwards from said inverted frusto-conical bafflewithin said container.
 6. The apparatus of claim 5, in which annularsubstantially horizontal means for separation of entrained liquiddroplets extends between said vertical cylindrical baffle and saidvertically oriented container, and said means extending from saidcontainer to remove the resulting scrubbed gas stream from saidcontainer is disposed between said means for separation of entrainedliquid droplets and the upper end of said inverted frusto-conicalbaffle.
 7. An apparatus for scrubbing solid and gaseous contaminantsfrom a gas stream which comprises a vertically oriented cylindricalcontainer, a first vertically oriented venturi scrubber within saidcontainer, said first venturi scrubber being defined by an upperinverted frusto-conical baffle which provides a converging section, anda throat section below said inverted frusto-conical baffle, said firstventuri scrubber being coaxially disposed in the upper section of saidcontainer and provided with means to adjust the venturi throat sectionto compensate for variation in gas flow, means to pass a gas streamcontaining solid and gaseous contaminants into said container above saidfirst venturi scrubber, whereby said gas stream flows downwards throughsaid first venturi scrubber and is accelerated to high velocity, meansto pass a first scrubbing liquid stream into said first venturiscrubber, whereby said first scrubbing liquid stream scrubs said gasstream in said first venturi scrubber and removes solid contaminants,means below said first venturi scrubber to separate first scrubbingliquid containing entrained solids from the resulting gas stream, meansto remove the separated first scrubbing liquid containing entrainedsolids from said container, said resulting gas stream containing gaseouscontaminant and being substantially free of solid contaminant, a secondvertically oriented venturi scrubber within said container, said secondventuri scrubber being defined by an upper inverted frusto-conicalbaffle which provides a converging section, and a throat section belowsaid inverted frusto-conical baffle, said second venturi scrubber beingcoaxially disposed in the lower section of said container and providedwith a fixed throat section of constant dimensions, means within saidcontainer to pass said resulting gas stream containing gaseouscontaminant from the upper section of said container downwards throughsaid second venturi scrubber, whereby said gas stream is accelerated tohigh velocity, means to pass a second scrubbing liquid stream into saidsecond venturi scrubber, said second scrubbing liquid stream being aselective absorbent for said gaseous contaminant present in saidresulting gas stream, whereby said second scrubbing liquid stream scrubssaid gas stream in said second venturi scrubber and dissolves gaseouscontaminant, means below said second venturi scrubber to separate secondscrubbing liquid containing dissolved contaminant from the residual gasstream, means extending from said container to remove the separatedsecond scrubbing liquid containing dissolved contaminant from saidcontainer, and means extending from said container to remove saidresidual gas stream of diminished contaminants content from saidcontainer said first and second venturi scrubbers being annular venturiscrubbers, each venturi scrubber being provided with a central conicalbaffle which is coaxial with said container, together with means to passscrubbing liquid downwards on the surface of said central conicalbaffle, said central conical baffle being coaxial with and spacedcentrally within said inverted frusto-conical baffle whereby saidcentral conical baffle and said inverted frusto-conical baffle define anannular converging gas flow passage, and means to pass scrubbing liquiddownwards on the upper surface of said inverted frusto-conical baffle,the central conical baffle of said first venturi scrubber beingvertically moveable whereby the throat section of said first venturiscrubber is adjustable in dimension.
 8. The apparatus of claim 7, inwhich said first venturi scrubber includes a first coaxial cylindricalbaffle which depends downwards from said upper inverted frusto-conicalbaffle, a central means below said coaxial cylindrical baffle forremoval of separated first scrubbing liquid containing entrained solidsfrom said container, a second coaxial cylindrical baffle within saidcontainer for gas diversion, said diversion baffle being spaced from thewall of said container and extending upwards from said central removalmeans and concentrically external to said first cylindrical baffle andterminating below said upper inverted frusto-conical baffle, and annularsubstantially horizontal means for separation of entrained liquiddroplets from said resulting gas stream, said annular separation meansextending between said first cylindrical baffle and said secondcylindrical baffle, whereby said resulting gas stream flows downwardsthrough said first cylindrical baffle, upwards through the annularpassage between said first cylindrical baffle and said secondcylindrical baffle, and downwards to said second venturi scrubberthrough the annular passage between said second cylindrical baffle andsaid container.
 9. The apparatus of claim 7, in which said gaseouscontaminant is sulfur dioxide, and said second scrubbing liquid streamcomprises an aqueous solution containing a dissolved alkaline componentselected from the group consisting of the hydroxides and carbonates ofsodium, potassium, calcium and magnesium.
 10. The apparatus of claim 7,in which a horizontal circular liquid distribution manifold is disposedabove the throat section of the second annular venturi scrubber, aplurality of spray nozzles depend downwards from said manifold, andmeans are provided to pass second scrubbing liquid to said manifold,whereby second scrubbing liquid is sprayed downwards into the throatsection of said second annular venturi scrubber.
 11. The apparatus ofclaim 7, in which a vertical rod extends coaxially downwards into saidcontainer, the conical baffle of said first vertically oriented annularventuri scrubber depending downwards from said rod with the apex of saidconical baffle being attached to the lower end of said rod, whereby saidconical baffle is coaxially suspended within said container, togetherwith means to vertically displace said rod, whereby the elevation ofsaid conical baffle within said container is adjusted and said firstvertically oriented annular venturi scrubber is thereby provided with anadjustable throat section.
 12. The apparatus of claim 11, in which saidmeans to pass first scrubbing liquId downwards on the surface of thecentral conical baffle of said first annular venturi scrubber is meansfor discharge of first scrubbing liquid at the apex of said conicalbaffle comprising a vertically oriented inverted frusto-conical conduit,said conduit being coaxially mounted about said rod at the upper end ofsaid container, the lower end of said conduit having at least onerestricted opening for downwards liquid flow adjacent to the apex ofsaid conical baffle, together with means to pass first scrubbing liquidinto said conduit at a controlled rate, whereby said conduit ismaintained at least partially filled with scrubbing liquid by saidrestricted opening and thereby maintains a liquid seal against upwardsflow of said contaminant-laden gas stream through said conduit.
 13. Theapparatus of claim 12, in which a vertical cylindrical sleeve iscoaxially mounted between said rod and the lower end of said conduit bya plurality of fixed spacers which are spaced apart and extend betweensaid rod and said sleeve, whereby said first scrubbing liquid flowsdownwards in the annular passage between said rod and said sleeve. 14.An apparatus for scrubbing solid and gaseous contaminants from a gasstream which comprises a vertically oriented cylindrical container, avertical rod, said rod extending coaxially downwards into saidcontainer, a first vertically oriented venturi scrubber within saidcontainer and below said rod, said first venturi scrubber being definedby a first central conical baffle and a first inverted frusto-conicalbaffle coaxially disposed in the upper portion of said container, saidfirst conical baffle depending downwards from said rod with the apex ofsaid conical baffle being attached to the lower end of said rod, wherebysaid conical baffle is coaxially mounted within said container, means tovertically displace said rod, whereby the elevation of said conicalbaffle within said container is adjusted to compensate for variation ingas flow, a vertically oriented inverted frusto-conical conduit, saidconduit being coaxially mounted about said rod at the upper end of saidcontainer, a vertical cylindrical sleeve, said sleeve being coaxiallymounted between said rod and the lower end of said conduit by aplurality of fixed spacers which are spaced apart and extend betweensaid rod and said sleeve, means to pass a first stream of scrubbingliquid into said conduit at a controlled rate, whereby said conduit ismaintained at least partially filled with scrubbing liquid by therestricted opening between said rod and said sleeve and therebymaintains a liquid seal against upwards gas flow through said conduit,and whereby said first stream of scrubbing liquid flows downwards in theannular passage between said rod and said sleeve, onto the apex of saidfirst conical baffle, and downwards on the outer surface of said firstconical baffle, said first inverted frusto-conical baffle dependingcoaxially downwards within said container from an upper contiguousconnection with the inner wall of said container, said first invertedfrusto-conical baffle being spaced from and concentrically about saidfirst conical baffle, whereby a downwardly converging annular gas flowpassage is defined between said first conical baffle and said firstinverted frusto-conical baffle, means to pass a second stream ofscrubbing liquid downwards on the inner surface of said first invertedfrusto-conical baffle, means to pass a gas stream containing solid andgaseous contaminants into said container above said first venturiscrubber, whereby said gas stream flows downwards through the convergingpassage between said first conical baffle and said first invertedfrusto-conical baffle and is accelerated to high velocity, and wherebysaid first and second streams of scrubbing liquid are entrained into thehigh velocity gas stream from the lower ends of said first baffles,solid contaminant being thereby entrained in the resulting liquiddroplets, means below said first venturi scrubber to separate scrubbingliquid containing entrained solids from the resulting gas stream, meansto remove the separated scrubbing liquid containing entrained solidsfrom said container, said resulting gas stream containing gaseouscontaminant and being substantially free of solid contaminant, a secondvertically oriented venturi scrubber within said container, said secondventuri scrubber being defined by a second central conical baffle and asecond inverted frusto-conical baffle which provide a convergingsection, and a throat section below said second baffles, said secondventuri scrubber being coaxially disposed in the lower section of saidcontainer and provided with a fixed throat section of constantdimensions, means within said container to pass said resulting gasstream containing gaseous contaminant from the upper section of saidcontainer downwards through said second venturi scrubber, whereby saidgas stream is accelerated to high velocity, means to pass a stream ofliquid absorbent for said gaseous contaminant into said second venturiscrubber, whereby said liquid absorbent scrubs said gas stream in saidsecond venturi scrubber and dissolves gaseous contaminant, means belowsaid second venturi scrubber to separate liquid absorbent containingdissolved contaminant from the residual gas stream, means extending fromsaid container to remove the separated liquid absorbent containingdissolved contaminant from said container, and means extending from saidcontainer to remove said residual gas stream of diminished contaminantscontent from said container.